1. Field of the Invention
This invention relates to a pneumatic tire, and more particularly to a pneumatic automobile tire including an inner tube consisting of a plurality of inflatable cell units, each being provided with an inflation and deflation valve device through which simultaneous inflation and deflation of the cell units may be achieved, whereby the puncturing of one cell unit would not deflate the entire tire.
2. Description of the Related Art
FIG. 1 is an illustration of a typical tire check valve used in combination with most pneumatic tires. The check valve opens when air pressure is applied, and closes when air pressure is removed, A valve cap (B) is provided to prevent air from seeping out of the tire. Without the valve cap (B), pressure applied on a shaft (A) of the check valve can open the check valve and release the air inside the pneumatic tire. This results in excessive tire wear if the tire is operated in the under-inflated condition.
U.S. Pat. No. 2,155,206 discloses a pneumatic tire which comprises a plurality of complementary cell units arranged in an annular formation. There is provided a plurality of inflation and deflation valve means for inflating the cell units and means for maintaining the cell units in the arranged annular formation. A main advantage of using the pneumatic tire of this patent is that the puncturing of one cell unit will not deflate the entire tire. A chain is operated so that the inflation and deflation valve means can be simultaneously opened to thereby deflate the cell units. One of the main drawbacks of the pneumatic tire disclosed in this patent is that the construction thereof is relatively complicated. The actual length of the chain is subject to temperature variations, which could cause untimely opening of the inflation and deflation valve means. Furthermore, operation of the chain does not ensure that all of the inflation and deflation valve means will be opened. Uneven deflation of the cell units is thus quite likely to occur.
Note that deflation of a pneumatic tire incorporating the tire check valve shown in FIG. 1 and the pneumatic tire disclosed in U.S. Pat. No. 2,155,206 can be easily accomplished by a prankster. In the former, the valve cap is simply removed and pressure is exerted on the shaft so as to deflate the pneumatic tire. In the latter, the chain is simply pulled so as to deflate the cell units.